SD卡fat文件系统移植
经过充分的研究，发现fatfs文件系统移植的比较简单！因为代码都已经被别人做好了！我们只需把io层稍稍做个处理就ok了；
至于sd卡的驱动请看我这篇博客：http://blog.csdn.net/ieczw/article/details/17378475
移植是以这个驱动为前提的！！
http://elm-chan.org/fsw/ff/00index_e.html
这个网站发布了所有版本的文件fatfs文件系统，我这次下载最新版的http://elm-chan.org/fsw/ff/ff9a.zip
直接解压，里面有两个文件，一个是src，另一个是doc；
把src放到自己的工程目录下面，并添加。首先看看00Readme.txt，我们主要是关注这些东西
FILES ffconf.h Configuration file for FatFs module. ff.h Common include file for FatFs and application module. ff.c FatFs module. diskio.h Common include file for FatFs and disk I/O module. diskio.c An example of glue function to attach existing disk I/O module to FatFs. integer.h Integer type definitions for FatFs. option Optional external functions. Low level disk I/O module is not included in this archive because the FatFs module is only a generic file system layer and not depend on any specific storage device. You have to provide a low level disk I/O module that written to control your storage device.所以我们主要修改的是diskio.c
DSTATUS disk_initialize (BYTE pdrv); DSTATUS disk_status (BYTE pdrv); DRESULT disk_read (BYTE pdrv, BYTE*buff, DWORD sector, BYTE count); DRESULT disk_write (BYTE pdrv, const BYTE* buff, DWORD sector, BYTE count); DRESULT disk_ioctl (BYTE pdrv, BYTE cmd, void* buff);
我们需要改的是这几个底层io函数，按照下面的修改，我想大家应该能懂！
/*-----------------------------------------------------------------------*/
/* Low level disk I/O module skeleton for FatFs (C)ChaN, 2012 */
/*-----------------------------------------------------------------------*/
/* If a working storage control module is available, it should be */
/* attached to the FatFs via a glue function rather than modifying it. */
/* This is an example of glue functions to attach various exsisting */
/* storage control module to the FatFs module with a defined API. */
/*-----------------------------------------------------------------------*/
#include "diskio.h" /* FatFs lower layer API */
#include "stm32_eval_sdio_sd.h"
/* Definitions of physical drive number for each media */
#define ATA 0
#define MMC 1
#define USB 2
#define SECTOR_SIZE 512U
/*-----------------------------------------------------------------------*/
/* Inidialize a Drive */
DSTATUS disk_initialize (
BYTE drv /* Physical drive nmuber (0..) */
)
{
return SD_Init();
}
/*-----------------------------------------------------------------------*/
/* Return Disk Status */
DSTATUS disk_status (
BYTE drv /* Physical drive nmuber (0..) */
)
{
return SD_GetStatus();
}
/*-----------------------------------------------------------------------*/
/* Read Sector(s) */
DRESULT disk_read (
BYTE drv, /* Physical drive nmuber (0..) */
BYTE *buff, /* Data buffer to store read data */
DWORD sector, /* Sector address (LBA) */
BYTE count /* Number of sectors to read (1..255) */
)
{
return (DRESULT)SD_ReadBlock(buff,sector << 9 ,count);
}
/*-----------------------------------------------------------------------*/
/* Write Sector(s) */
#if _READONLY == 0
DRESULT disk_write (
BYTE drv, /* Physical drive nmuber (0..) */
const BYTE *buff, /* Data to be written */
DWORD sector, /* Sector address (LBA) */
BYTE count /* Number of sectors to write (1..255) */
)
{
return (DRESULT)SD_WriteBlock((uint8_t *)buff,sector << 9 ,count);
}
#endif /* _READONLY */
/*-----------------------------------------------------------------------*/
/* Miscellaneous Functions */
DRESULT disk_ioctl (
BYTE drv, /* Physical drive nmuber (0..) */
BYTE ctrl, /* Control code */
void *buff /* Buffer to send/receive control data */
)
{
return RES_OK;
}
unsigned short get_fattime(void){
return 0;
}这些修改完后，如果你直接编译会出现如下错误：
..\fatfs\cc936.c(11): error: #35: #error directive: This file is not needed in current configuration. Remove from the project.
找到cc936.c，他的头文件是这样定义的
/*------------------------------------------------------------------------*/ /* Unicode - OEM code bidirectional converter (C)ChaN, 2009 */ /* */ /* CP936 (Simplified Chinese GBK) */ /*------------------------------------------------------------------------*/ #include "../ff.h" #if !_USE_LFN || _CODE_PAGE != 936 #error This file is not needed in current configuration. Remove from the project. #endif
他是找不到USE_LFN或者_CODE_PAGE !=936
那么可能头文件处理问题，大家应该发现问题了，把头文件修改下：#include "ff.h"
为什么要用936的呢？大家看ffconf.h，有这么一段注释
/*---------------------------------------------------------------------------/ / Locale and Namespace Configurations /----------------------------------------------------------------------------*/ #define _CODE_PAGE 936 /* The _CODE_PAGE specifies the OEM code page to be used on the target system. / Incorrect setting of the code page can cause a file open failure. / / 932 - Japanese Shift-JIS (DBCS, OEM, Windows) / 936 - Simplified Chinese GBK (DBCS, OEM, Windows) / 949 - Korean (DBCS, OEM, Windows) / 950 - Traditional Chinese Big5 (DBCS, OEM, Windows) / 1250 - Central Europe (Windows) / 1251 - Cyrillic (Windows) / 1252 - Latin 1 (Windows) / 1253 - Greek (Windows) / 1254 - Turkish (Windows) / 1255 - Hebrew (Windows) / 1256 - Arabic (Windows) / 1257 - Baltic (Windows) / 1258 - Vietnam (OEM, Windows) / 437 - U.S. (OEM) / 720 - Arabic (OEM) / 737 - Greek (OEM) / 775 - Baltic (OEM) / 850 - Multilingual Latin 1 (OEM) / 858 - Multilingual Latin 1 + Euro (OEM) / 852 - Latin 2 (OEM) / 855 - Cyrillic (OEM) / 866 - Russian (OEM) / 857 - Turkish (OEM) / 862 - Hebrew (OEM) / 874 - Thai (OEM, Windows) / 1 - ASCII only (Valid for non LFN cfg.) */所以，因为我们是中国人，所以我们要用936！哈哈。。。
然后编译又出现另一个问题：
..\output\stm32.axf: Error: L6218E: Undefined symbol get_fattime (referred from ff.o).
这个我们需要自己添加，我在上面修改diskio.c的时候已经添加了。
这些做完之后，也算移植玩了，简单吧，至于如何使用，我们还是看下载网页：http://elm-chan.org/fsw/ff/00index_e.html
或者双击doc/目录下的00index_e.html
Application Interface FatFs module provides following functions to the applications. In other words, this list describes what FatFs can do to access the FAT volumes. f_open - Open/Create a file f_close - Close an open file f_read - Read file f_write - Write file f_lseek - Move read/write pointer, Expand file size f_truncate - Truncate file size f_sync - Flush cached data f_forward - Forward file data to the stream f_stat - Check existance of a file or sub-directory f_opendir - Open a directory f_closedir - Close an open directory f_readdir - Read a directory item f_mkdir - Create a sub-directory f_unlink - Remove a file or sub-directory f_chmod - Change attribute f_utime - Change timestamp f_rename - Rename/Move a file or sub-directory f_chdir - Change current directory f_chdrive - Change current drive f_getcwd - Retrieve the current directory f_getfree - Get free clusters f_getlabel - Get volume label f_setlabel - Set volume label f_mount - Register/Unregister a work area f_mkfs - Create a file system on the drive f_fdisk - Divide a physical drive f_gets - Read a string f_putc - Write a character f_puts - Write a string f_printf - Write a formatted string f_tell - Get current read/write pointer f_eof - Test for end-of-file on a file f_size - Get size of a file f_error - Test for an error on a file里面对每个函数都做了说明，这样就有点像linux操作系统里面的文件io操作了。
我们可以任意点击去一个函数，里面都有例程，我们可以用这些例程来测试下
/* Read a text file and display it */
FATFS FatFs; /* Work area (file system object) for logical drive */
int main (void)
{
FIL fil; /* File object */
char line[82]; /* Line buffer */
FRESULT fr; /* FatFs return code */
/* Register work area to the default drive */
f_mount(&FatFs, "", 0);
/* Open a text file */
fr = f_open(&fil, "message.txt", FA_READ);
if (fr) return (int)fr;
/* Read all lines and display it */
while (f_gets(line, sizeof line, &fil))
printf(line);
/* Close the file */
f_close(&fil);
return 0;
}
好，基于STM32的fatfs文件系统移植就到这里了！！！！
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